VolumeBureau of Standards Journal of Research, Vol. 12, No. 6 , p. 735. Research Paper 686 (RP686) PublisherNational Bureau of Standards Pages22 Possible copyright statusThe Bureau of Standards Journal of Research is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. However, please pay special attention to the individual works to make sure there are no copyright restrictions indicated. Individual works may require securing other permissions from the original copyright holder. LanguageEnglish Call numberQC1 .U52 1934 V 12 Digitizing sponsorNIST Research Library Book contributorNIST Research Library CollectionNISTJournalofResearch; NISTresearchlibrary; fedlink; americana NotesTitle page is also the Contents page.